1. Field of the Invention
The present invention is directed to structural members for use in building construction and in particular to roof truss systems for construction of roof framing for supporting roofs.
2. Description of the Prior Art
A truss is a generally rigid frame member designed to support a structure, such as a roof or a floor. Trusses come in many shapes and sizes for a variety of applications.
The building of roof trusses on the building site in residential and in small commercial buildings is an expensive and time-consuming operation. In addition, where a large number of such trusses need be built, they rarely turn out to be perfectly uniform. As a result, the building industry has gone to the prefabricated roof truss, which eliminates the costly on-site labor time.
Roof trusses for commercial and residential buildings are typically prefabricated using wooden beams and metal joiner plates. Such prefabricated structures are large and heavy and must be shipped from the factory to the building site in small numbers on a large truck. However, shipping height and width restrictions can impose constraints on truss geometry, particularly where the trusses are to be shipped via a public highway system.
As a result of shipping height and width restrictions, it is common for truss designers to design many trusses as “piggy-backs,” which include small portions of the overall truss design and are more easily transported to the construction site. Once the piggy-back trusses are received at the building site, they are usually mounted on top of each other to obtain the desired roof geometry. When piggy-back trusses are used, special field framing and bracing is typically required to ensure that loads are properly transferred and structural stability is maintained. Although piggy-back trusses solve many problems encountered when shipping the trusses to the construction site, such truss arrangements typically result in additional material handling and set up costs which increase building construction costs.
An alternative to piggy-back trusses is to fabricate the trusses with one or more hinge assemblies to connect the structural members which form the trusses and, thus, render the truss collapsible for shipping purposes.
U.S. Pat. No. Ser. 5,553,961 discloses a hinge for use in connecting two coplanar wooden structural members of a wooden truss structure enabling folding of the structure to reduce its height for transport over the road. The hinge includes two pivotally interconnected plates each having teeth for nailing, them to the wooden members and one having fingers for engagement with a surface of a wooden member for accurate alignment.
U.S. Pat. No. 6,401,422 discloses a hinge connector for interconnection of disconnected truss members. The connector includes an elongate sheet metal plate having nailing teeth adapted to be driven into a truss member for permanently attaching it to one member. The truss can be collapsed and transported to the building site with the truss members disconnected.
The hinge assemblies set forth in these U.S. Patents are primarily for use with wooden trusses and are not well suited for trusses formed from, for example, steel or other metal materials.
U.S. Pat. No. 3,760,550, discloses a collapsible truss structure where the truss structure may be formed of steel channel members. Bolted arrangements are provided for pivotably and slidably connecting the members that form the truss.
U.S. Pat. No. 6,634,152 discloses a jackknife foldable roof truss including left and right heel sections, a jackknife foldable peak section and a center bottom chord.
Such arrangements are generally not cost effective to transport, manufacture and install. Thus, a hinged roof truss assembly that provides desired structural strength while reducing transportation, material handling and set up costs resulting in decreased building construction costs would be desirable.